A University of Virginia graduate student has developed a biofeedback-based system that helps smartphones select music that will help get their owners' heart pumping during exercise, or slow it down when they want to cool down or relax. "Whether I am driving, jogging, traveling or relaxing -- I never find the appropriate music to listen to," said Shahriar Nirjon, a doctoral student in computer science in the School of Engineering and Applied Science. "I believe there are many like me. The problem is: The heart wants to hear something, but our music player does not understand the need. My joy was in connecting them together -- in a non-invasive and cost-effective way."